Is it possible to delete forum row's from mobile view using Form API ? How can I do It?
I am not sure I understand what you want to do, can you try to be more specific and also what is the Form API.
There's no API for form, but if you build a form using 'User Input' components, then you can decide that a component is hidden on mobile.
If you need to do anything for mobile/desktop only using code, see here how to determine whether is it a mobile view or a desktop view.